An evaporator or a condenser usually includes a multiplicity of tubular circuits, comprising a succession of parallel U tubes, connected with each other by means of curved tube sections in such a way as to form, for each tubular circuit, a serpentine path, with fins through which the tubes extend. These fins are substantially perpendicular to the tubes and are in heat conducting contact with the latter. The evaporator or condenser further typically includes a distributor device for the fluid, which is for example a refrigerant fluid of the Freon type, this distributor device being connected to one end of the said circuits and to a feed tube for the fluid; it also includes a fluid collector device which is connected to the other end of the tubular circuits and to an exhaust tube for the fluid.
In addition, in an evaporator of this kind, the tubular circuits are arranged in such a way that the segments of the parallel U tubes forming part of the circuits are grouped so that the said segments are either juxtaposed with each other or superimposed on each other.
This arrangement is necessary in order to ensure a change of state of the refrigerant fluid in the tubular circuits so that the fluid, after undergoing heat exchange with another fluid (for example ambient air passing through the evaporator) will always be in the required second state by the time it reaches the outlets of the tubular circuits.
To this end, the fluid distributor device conventionally includes thin or capillary tubes which are connected to the inlets of the tubular circuits and to the feed tube, in such a way that the fluid is substantially evenly distributed between the circuits.
The collector device allows the exhaust tube and the outlets or the tubular circuits to be connected together through connecting tubes which are sealingly fixed to the collector and to the said outlets.
Such a collector device is formed from the free ends of the tubes constituting the circuits, by flattening and enlarging each of these free ends into general shape of a flat nozzle, having a mouth larger in the radial direction than the tube itself.
The flat nozzle thus formed has two parallel walls connected at their ends through semi-cylindrical walls, and is adapted to receive the ends of the connecting tubes. Its dimensions are so chosen that, firstly, the distance between the parallel walls is substantially equal to the diameter of a connecting tube, and secondly, the distance between the two semi-cylindrical walls is substantially equal to the sum of the diameters of those connecting tubes which are located within the nozzle. The connecting tubes are disposed side by side in the nozzle, so as to lie in a common plane and to extend in a common direction.
Once the ends of the connecting tubes have been placed in the mouth of the flat nozzle, they are secured to it in a fixed and sealed manner, for example by brazing.
It has however been established that the arrangement described above has certain disadvantages. In order to obtain the flat nozzle shape, it is necessary to carry out a lengthy and costly forming operation on the free end of the tube of each tubular circuit. Even then, the number of connecting tubes which can be received within such a nozzle is not as large as may be desirable, since the dimensions of the nozzle depend on those of the free end of the circuit tube. In addition, in order to connect the ends of the connecting tubes within the nozzle, the brazing operation entails a danger of introducing braze metal into undesirable places, for example into the mouths of the connecting tubes connected to the tubular circuits. This adversely affects satisfactory operation of the tubular circuits, even to the extend of the entry to the connecting tubes becoming totally obstructed, and consequently the outlet of a tubular circuit being similarly obstructed.